India's Cabinet has approved a proposed $4 billion deal to purchase military transport aircraft from the U.S. aerospace giant Boeing, the largest defense deal ever made between the two countries.

Sources say the deal to buy 10 C-17 aircraft was approved during a recent meeting of the Cabinet's committee on security affairs.

Indian officials say the aircraft will be purchased as a government-to-government sale and will need final approval by both sides.

Months ago, India rejected bids from Boeing and Lockheed Martin to supply 126 fighter jets to the Indian air force. The C-17 is a large transport aircraft capable of carrying combat equipment and troops across long distances while being able to land at smaller airstrips.

India is expected to spend at least $80 billion in the coming years to upgrade its military.